Re: [q-lang-users] "and then" and stack usage

[ww <wwa...@ea...>]

----- Original Message -----
From: "Albert Graef" <Dr....@t-...>
To: <q-l...@li...>
Cc: <wwa...@ea...>
Sent: Sunday, February 15, 2004 4:10 PM
Subject: Re: [q-lang-users] "and then" and stack usage


> /me wrote:
> > ww wrote:
> >
> >> I've been exploring Q recently and I've noticed that "and then" doesn't
> >> seem to run in constant space. From it's definition (in the docs), I
was
> >> expecting that it could reuse the stack frame but that doesn't seem to
> >> be the case. Am I missing something?
> >
> > I thought about this problem a little more -- it's really been haunting
> > me. ;-) So here's the result of my contemplations...
> >
> > [snipped]
>
> I thought about it still some more, and finally decided that this is
> really a bug that needs to be solved. Said and done. ;-) So in cvs you
> can now find a new version of the interpreter that is fully
> tail-recursive. That is, tail calls are now optimized for builtins and
> special arguments just as for user-defined rules. Thus, e.g., (=) and
> `all' on lists now run in constant stack space, without the need to
> rewrite anything. Enjoy! :)
>
> Albert
>
> --
> Dr. Albert Gr"af
> Email:  Dr....@t-..., ag...@mu...
> WWW:    http://www.musikwissenschaft.uni-mainz.de/~ag

Thank you! What a nice surprise. I'll try the new version this
weekend.

Walt